A method for inhibiting the growth of bacteria using a synergistic mixture of sodium dimethyldithiocarbamate and formaldehyde

ABSTRACT

A method for inhibiting microbial growth in substances and a biocidal composition therefor employing a synergistic mixture of sodium dimethyldithiocarbamate and formaldehyde.

United States Patent Werlein et al. 1 Oct. 17, 197 2 [5 METHOD FORINHIBITING THE 3,173,832 3/1965 Harris ..167/22 GROWTH OF BACTERIA USINGA 3,198,699 8/1965 Boogaart ..l67/22 YNER I MIXTURE 0 SODIUM 3,223,51312/1965 Geary l/2.3 DIMETHYLDITHIOCARBAMATE AND OTHER. PUBLICATIONSFORMALDEHYDE Inventors: Eugene R. Werlein; John W. Hollingsworth; LyndonD. Pins on,

Appl. No.: 841,129

US. Cl ..424/286, 424/334 1m. Cl. ....-.....A0ln 9/02, AOln 9/12, A0ln9/24 Field of Search ..424/286, 333, 334, 342

References Cited UNITED STATES PATENTS 4/1950 Flenner ..l67/22 Chem.Abst., Murata et al., Vol. 61, 1964 p. l 193d.

Primary Examiner-Albert T. Meyers Assistant Examiner-Allen J. RobinsonAttorney-Robert W. Mayer, Daniel Rubin, Raymond T. Majesko, Roy L. VanWinkle, William E. Johnson, Jr. and Roderick W. MacDonald l [57]ABSTRACT A method for inhibiting microbial growth in substances and abiocidal composition therefor employing a synergistic mixture of sodiumdimethyldithiocarbamate and formaldehyde.

1 Claim, No Drawings METHOD FOR INHIBITING THE GROWTH OF BACTERIA USINGA SYNERGISTIC MIXTURE OF SODIUM DIMETIIYLDITIIIOCARBAMATE ANDFORMALDEIIYDE BACKGROUND OF THE INVENTION It is desirable to have abiocide which can be incorporated in substances be they solid, liquid,or gases, and which will have the effect of inhibiting microbial growthin those substances since it is a well known fact that microbial floracan cause substantial corrosion damage when contacted with conventionalapparatus such as iron containing pipes, vats, and the like, and canthemselves create objectionable odors.

In addition, in substances suitable for special uses such as drillingfluids, solutions used in the paper makin gindustry, and the like,microbial flora can materially alter the physical characteristics of thesubstance containing the flora. For example, deterioration in fluid losscontrol and/or viscosity control in a drilling fluid can occur due tomicrobial action. Drilling fluids which are especially susceptible tomicrobial degradation are those which contain organic materials suitableas food for the microbes, e.g., those containing starch, polymer, andthe like. The term drilling fluids used herein is meant to includedrilling muds (water base or hydrocarbon, e.g., oil base) used fordrilling in,

completing, or working over wells, for packer fluids, and the like.

SUMMARY OF THE INVENTION According to this invention there is provided abiocidal composition which is composed of a mixture of at least onealdehyde as hereinafter defined and at least one carbamate ashereinafter defined.

Also according to this invention there is provided a method forinhibiting microbial growth in a substance wherein there is incorporatedin the substance an effective microbial growth inhibiting amount of thebiocidal composition of this invention.

The method and composition of this invention is applicable to a widevariety of solid liquid and gaseous substances so long as the biocidalcomposition can be incorporated in the substance and the substance issubstantially chemically inert to the biocidal activity of the biocidalcomposition. Thus, the biocidal composition and method of this inventionare useful in the abovementioned drilling fluids, the paper makingindustry,

paints, cutting oils or fluids, and any other system requiring microbialinhibition with which they are compatible.

Accordingly, it is an object of this invention to provide a new andimproved biocidal composition. It is another object to provide a new andimproved method for inhibiting microbial growth in substances. It isanother object to provide a biocidal composition and method forinhibiting microbial growth particularly adaptable to drilling fluids aspresently used in drilling wells.

Other aspects, objects, and advantages of the invention will be apparentto those skilled in the art from the disclosure and the appended claims.

DETAILED DESCRIPTION OF THE INVENTION According to this invention thebiocidal composition is composed of (l at least one aldehyde selectedfrom the group consisting of paraformaldehyde of the formula l-IO(CI-I20),l-I where x varies from 2 to 5,000, preferably 2 to 100, inclusive,and aldehydes represented by the formula where R is one of hydrogen,alkyl having from one to 10, preferably from one to five, inclusive,carbon atoms per molecule, cycloalkyl having from four to 10, preferablysix to eight, inclusive, carbon atoms per molecule, and aromatic havingfrom six to 14, inclusive, carbon atoms per molecule; and (2) at leastone carbamate of the formula where R1 is defined in the same manner as Rhereinabove for the aldehydes, Y is one of oxygen and sulfur, preferablysulfur, and M is one of an alkali metal and an alkaline earth metal,preferably zinc, sodium, potassium, rubidium, lithium, calcium, andmagnesium.

Suitable aldehydes include formaldehyde, acetaldehyde, n-butyraldehyde,iso-butyraldehyde, cyclobutylaldhyde, cyclohexylaldehyde,cyclooctylaldehyde, cyclodecylaldehyde, benzaldehyde, and the like.

Suitable carbamates include dimethyldithiocarbamates,dimethylcarbamates, diethylcarbamates, octyldecylcarbamates,cyclohexylcarbamates, cyclononylcarbamates, benzylcarbamates, andnapthylcarbamates of one of zinc, sodium, potassium, calcium, magnesium,or the like.

The aldehyde and carbamate components of the composition of thisinvention are combined in a weight ratio range of the aldehyde to thecarbamate of from about 0.1/1 to about 1/0. 1 preferably from about0.5/1 to about l/0.5.

The composition can be prepared in any conventional manner such as bymixing the components together under ambient conditions of temperature,pressure, and atmosphere, although superambient or subambient pressuresand temperatures can be employed as well as inert atmospheres so long asthe biocidal activity of the resulting composition is substantiallyunaffected.

The resulting biocidal composition is then incorporated into thesubstance to be protected in an effective microbial growth inhibitingamount. The incorporation can also be carried out in any conventionalmanner but will generally be intimately mixing the biocidal compositionwith the substance to be treated such as high shear or gentle mixingunder conditions set forth hereinabove for the mixing of the biocidalcomposition components themselves. When the substance to be treated is asolid it can be inoculated with the biocidal composition or coatedtherewith such as by subdividing the solid and coating the particleswith the biocidal composition by mixing. The ultimate desired result isthe intimate and homogeneous mixing of the biocidal composition and thesubstance so that microbial flora in all parts of the substance arelikely to contact a portion of the biocidal composition.

The amount of biocidal composition incorporated in a particularsubstance will vary widely depending upon the substance itself,thebiocidal composition itself, the conditions of use of the substance,the extent of prior contamination of thesubstance by microbes, the timeperiod of growth inhibition desired, and the like. Thus, it issubstantially impossible to quantitatively state a general minimumeffective amount of the biocidal composition. There is no maximum amountfroma biocidal point of view although large excesses of the biocidalcomposition may not be desirably used because of economicconsiderations. However, generally atleast about 5 parts per million ofthe biocidal composition can be employed based on the total parts of thesubstance to be treated.

The biocidal composition and method of this invention is applicable tomicrobes in general and particularly to sulfate reducing microbes.l-lowever, this invention is generally applicable to aerobic andanaerobic bacteria. Examples of sulfate-reducing bacteria to which thisinvention is applicable include Division: Protophyta ClasszSame Order:Eubacterialles SpeCieSINigrificans and perhaps others EXAMPLE A samplesubstance for treatment was formed by intimately mixing at ambientconditions of temperature and pressure and under ambient air atmosphere,315 milliliters of sea water, 94 grams of bentonite, 6 grams of amixture of chrome lignite and chrome lignosulfonate in a l lignite to 2lignosulfonate weight ratio, 2 milliliters of a 50 per cent aqueoussolution of sodium hydroxide, and 35 milliliters of Diesel oil.

Seventy gram portions of this sample substance were taken'for each test.Each 70 gram portion was contaminated with equal amounts of a mixedculture of micro-organisms containing both aerobic and anaerobicbacteria and particularly containing sulfate-reducing bacteria. Eachsample was treated with an additive of formaldehyde in a 40 weight percent water solution, sodium dimethyldithiocarbamate, or a combination ofthe 40 weightper cent solution of formaldehdye and sodiumdimethyldithiocarbamate in a ll] weight ratio. Onesample was leftuntreated by formaldehyde or car bamate or a combination thereof. Thisblank was tested alongwith the other test samples to make sure thatmicrobial growth would have taken effect. In each instance the blankshowed substantial microbial growth. Various concentrations of each ofthe additives was employed to obtain the minimum concentration of eachmaterial necessary to prevent growth of bacteria in the sample after a15 minute period, after a 24 hour period, and after a 7 day periodfollowing treatment of the sample.

Two media were employed to determine bacterial growth subsequent totreatment of the samples with various additives to inhibit microbialgrowth. The first media, was a standard, commercial preparation,nutrient agar, Baltimore Biological Laboratory, Baltimore, Md. Thesecond media was the recommended media for cultivation ofsulfate-reducing bacteria as set forth in Recommended Practice number38( 1958), American Petroleum institute, and was composed of 1 gram ofmagnesium sulfate, 1 gram of potassium biphosphate, 0.1 gram of ammoniumsulfate, 0.l gram of sodium sulfite, 0.1 gram of ascorbic acid, 3.5milliliters of sodium lactate, 1 gram peptone, 1 gram yeast extract, 3grams agar, and, 1,000 milliliters distilled water. After each samplehad been treated with the additive and the treated sample allowed to situnder ambient conditions for its designated period of time of 15minutes, 24 hours,-or 7 days, subsamples of approximately 0.1 cc weredrawn out of each sample with a sterilized pipette, mixed with liquifiednutrient agar medium held at 35 C., then poured into a sterile petridish and allowed to solidify prior to incubation. A second 0.1 ccsub-sample was removed from the treated sample and mixed with thesterile, liquified API media in a 13 X mm, screw-top test tube, beingheld at 35 C. To prevent solidification, and then allowed to solidify atroom temperature prior to incubation. All tests were done in duplicatewith a blank untreated sample included in the series. The. nutrient agarsamples were incubated for 36 hours at 32 C. and API samples wereincubated 1 week to 10 days at 32C. After incubation, each sample wasexamined for microbial presence therein.

Each additive was checked at 50 to 3,000 ppm, based on active ingredientof the additive, in increments of 50 ppm, to determine the minimumconcentration of the additive necessary to substantially completelyinhibit microbial growth over a period of 7 days. The results of thisprogram were as follows:

TABLE l Concentration inppm necessary to prevent any microbial Additivegrowth for 7 days 1) Formaldehyde 1750 2) Sodium dimethyldithiocarbamategreater than 3000 3) Mixture of l) and 2) 1250 um after the 7 day testperiod.

It can further be seen from the table that when a l/ 1 weight ratio ofthe formaldehyde and sodium dimethyldithiocarbamate were combined toform a biocidal composition which was then added to a sample, thecombination of these two materials was very substantially more effectiveas a biocide than either of the two materials taken alone. This isevidenced by the fact that with only 1250 ppm of the combination offormaldehyde and sodium dimethyldithiocarbamate microbial growth wasprevented for the 7 day period.

Thus, the combination of the aldehyde and carbamate gave biocidalresults better than the predictable additive results from the use of thetwo components by

